1. Field of the Invention (Technical Field)
The present invention relates to methods to desensitize metastable intermolecular composite materials.
2. Description of Related Art
Metastable Intermolecular Composites (MICs) are materials comprised of nanoscale composite energetic materials, often a metal and an oxidizer. Similar in composition to classical composites, MICs differ in that the individual particle sizes are on the nanometer scale (10−9 m) instead of millimeter or sub-millimeter (10−4 m to 10−3 m). This significant change in spatial scale significantly changes the chemical and mechanical properties, enabling a new set of behaviors. For example, instead of burning at tens of millimeters per second, MICs are capable of combustion velocities of tens of meters per second up to kilometers per second. These differences make these a new class of materials.
These materials have found a variety of possible applications including as electric and percussion igniters or primers. See, for example, U.S. Pat. No. 5,717,159 for percussion primers. However, a significant practical issue limits their widespread and scaled production. This issue is the sensitivity of these nanoscale materials to electrostatic discharge (ESD) and friction. For applications such as lead-free igniters or primers, the sensitivity is needed for the application to work. Specifically, a small hot spot caused by the heating of the bridgewire must be sufficient to ignite the mixture in an electric igniter. Similarly, the material must be friction sensitive enough to be reliably ignitable by the action in a percussion primer. Ideally what is needed is a material that can be desensitized to friction and ESD so that large amounts of the material can be handled, yet re-sensitized when configured in the final desired application for the particular material.
While other processes may achieve similar results (such as a hydrous process involving modification of nanoscale aluminum to reduce MIC sensitivity), these require more complex processing, especially to produce a MIC material of as high a quality as the starting MIC material. Furthermore, the present invention permits the undisturbed use of organic polymers in conjunction with the MIC material.